(1) Field of the Invention
This invention relates to a sewing apparatus for displaying a stitch pattern and forcibly supplying a thread based on the displayed stitch pattern.
(2) Description of the Prior Art
An automatic thread supply device used, for example, in an overlocking sewing apparatus automatically supplies a needle thread and upper and lower looper threads. Since different types of threads are required in different lengths to form a stitch, such a device is equipped with a plurality of thread holding devices. A period for which each thread holding device is releasing the thread must be adjusted by an operator.
Although there is a certain relationship between the required length for each thread and the pattern of stitch, it is extremely hard even for a skilled operator to determine how much of each thread is required to get a desired pattern of stitch. Therefore, many tries have to be made before the desired pattern of stitch is obtained, which drastically lowers the operating efficiency of the sewing apparatus.